Fig. 1. Confocal system chromatographic focusing principle

Fig. 2. Combined response of two reflective layers

Fig. 3. Internal light tracing model of wafer

Fig. 4. Block diagram of laser confocal semiconducting wafer thickness measurement sensor system

Fig. 5. Physical map of laser confocal semiconducting wafer thickness measurement sensor system

Fig. 6. Influence of Δn on T_phs with different NA

Fig. 7. Influence of NA discrepancy on Δn and Δn

Fig. 8. Relationship between M_OP and Δu with different f₀

Fig. 9. Axial response curves for different pinhole sizes

Fig. 10. Variation of curve parameters with different normalized radii

Fig. 11. Optical resolution testing

Fig. 12. Samples of different semiconductor wafers

Fig. 13. Axial response curve of laser confocal sensor

Fig. 14. Curves of measurement results for different wafers